Machine-Type Communication (MTC) is an important revenue stream for operators and has a huge potential from the operator perspective. It is efficient for operators to be able to serve MTC user equipment (UE) using already deployed radio access technology. Therefore 3GPP Long Term Evolution (LTE) has been investigated as a competitive radio access technology for efficient support of MTC. Lowering the cost of MTC UE is an important enabler for implementation of the concept of “internet of things”. MTC UE used for many applications will require low operational power consumption and are expected to communicate with infrequent small burst transmissions. In addition, there is a substantial market for the Machine-to-Machine (M2M) use cases of devices deployed deep inside buildings which would require coverage enhancement in comparison to the defined LTE cell coverage footprint.
3GPP LTE Rel-12 has defined UE power saving mode allowing long battery lifetime and a new UE category allowing reduced modem complexity. In Rel-13, further MTC work is expected to further reduce UE cost and provide coverage enhancement. Cost reduction is enabled at least in part by introducing reduced UE bandwidth, e.g., of 1.4 MHz in downlink and uplink within any system bandwidth (also referred to as carrier bandwidth).
Reducing UE bandwidth, however, in turn introduces challenges in the UE's ability to report pertinent channel state information (CSI) to the network. LTE for example conventionally supports wideband channel quality indicator (CQI) reporting, whereby a UE reports a CQI value representing the effective channel quality over the entire system bandwidth (e.g., for each component carrier when carrier aggregation is used). This CQI reporting mode is not usable by reduced bandwidth UEs.